What they don’t tell you however, is that the virtual disk must be fully removed from the VirtualBox Virtual Media Manager before the command will run successfully (if you have been using the virtual disk previously in a virtual machine in VirtualBox).

Allow to choose a file format for the output file different from the file format of the input file.

variant

Allow to choose a file format variant for the output file. It is a comma-separated list of variant flags. Not all combinations are supported, and specifying inconsistent flags will result in an error message.

type

Only honored if –remember is also specified. Defines what kind of hard disk type this image should be.

remember

Keep the destination image registered after it was successfully written.